| 摘要 |
PURPOSE:To obtain a heat-resistant vessel which is not eroded by hydrofluoric acid, by making a vessel with Al-SiC material and providing the surface of the vessel with a porosity less than a specified value and further by providing a flange having a less surface roughness less than a specified figure at one end or both ends of the vessel. CONSTITUTION:A hydrofluoric acid vessel is made of Al-SiC material and the porocity of the vessel surface is less than 0.5% and also a flange having a surface roughness less than 0.5mum is provided at one end or the both ends of the vessel. The reason why the porocity on the vessel surface is restricted to be within 0.5% is that hydrofluoric acid solution percolates through the pores to damage it on heating when the porocity is more than 0.5%. The reason why the surface roughness of the flange surfaces 14a, 15a are restricted withind 0.5mum exists in protecting the heated hydrofluoric acid solution from leaking through the vessel by providing a groove for the O-ring on the companion flange to closely fit to the flange of the vessel and by fitting the O-ring on the flange. |
